E _g of substances obtained from linear fitting in different conditions^33–43.

Substance	Fitting Eg (eV)				Reference Eg (eV)
	T (20Zn)	T (30Al)	T (20Zn + 20Al)	T (blank)
FeO	2.4	2.4	2.4	2.3–2.4	2.3–2.4
Fe2O3	2.2	2.1	2.2	2.1–2.2	2.1–2.2
ZnFe2O4	1.8	—	1.8	—	1.8–1.9
ZnO	3.2–3.6	—	3.2–3.6	—	3.2–3.6
ZnAl2O4	—	—	3.85	—	3.8–3.9
FeAl2O4	—	1.78	1.78	—	1.78
MnO	3.9–4.0	4.0	3.6–4.0	3.6–4.0	3.6–4.0
MnFe2O4	1.76	1.76	1.76	1.76	1.76